十二烷基苯磺酸钠(DBS)对原生动物的毒性效应

STUDY ON THE TOXIC EFFECTS OF SURFACTANT DBS ON PROTOZOA

进行了十二烷基苯磺酸钠(DBS)对原生动物的种、种群和群落等三个不同生物学组织水平的毒性试验。结果表明:DBS对5种原生动物的急性毒性作用没有种的特异性(p>0.05)。半致死浓度12h-LC_(50)在7.0—10.47ppm之间;对美洲四膜虫种群的急性毒性作用,12h—LC_(50)为17.21ppm;对其呼吸率的影响,表明其效应浓度为12.84ppm(p<0.05);3—40ppm DBS,对微型生物群落的结构、功能有不同程度的影响。结构参数有原生动物种类组成和种类数;功能参数有原生动物群集过程、微型生物群落的P/R化。反映原生动物群集过程的3个参数S_(eq)、G和T_(90％)中的S_(eq)与DBS浓度的自然对数成直线负相关,由其回归方程Y=29.7281—5.6722X(p0.05)推算出DBS对原生动物群落的EC50、EC20和EC5分别为4.684、0.51和0.1681ppm。以种和种群水平的12h-LC_(50)为基础,推算出的MATC,在AF为0.1时,分别为0.7和1.721ppm;在AF为0.01时,MATC为0.07和0.1721ppm。比较来自种和种群水平的MATC与来自群落水平的EC20、EC5,后者更具科学性和环境真实性。因此,对于东湖,MATC不得高于0.5ppm,最好低于0.17ppm。

Toxic tests of surfactant DBS (Dodecyl Benzene Sulfonate) were carried out at three biological organization levels: species, population. and community. Results showed that there were no specific differences in the acsute toxicity of DBS among five protozoan species: Paramecium caudatum, Tetrahymena americanis, T. piqmentosa, T. borealis 3IV WW0, T. borealis 3II VM665, and T. tropicalis DIV TC 89 (P>0.05). 12h-LC_(50) was between 7.0 and 10.47 ppm. At the population level of Tetrahymena americanis, the 12h-LC_(50) was 17.21 ppm; the effective concentration of DBS was 12.84 ppm (P<0.05), based on the respiration of Tetrahymena americanis, determined by the Gilson Differential Respirometer. From low (3 ppm) to high (40 ppm) concentrations the toxic effects of DBS on the structure and function of the microbial community increased. The structural parameters included the number of protozoan spe-ciesand their composition. The functional parameters included the colonization process (S_(eq), G, T_(90%)) and the ratio of photosynthesis to respiration. There was a strong negative correlation between S_(eq) and natural logarithm of DBS concentration; their relationship can be described by the regression equation S_(eq) = 29.7281—5.6722 InC. (P<0.05). The effective concentrations (EC) were calculated from the equation, and the EC_(50), EC_(20), EC_5 were 4.684, 0.51, 0.1681 ppm respectively. Based on 12h-LC+(50) at species and population levels, MATC was 0.70 and 1.721 ppm respectively when AF was 0.1, and 0.07, 0.1721 ppm respectively when AF was 0.01. Comparison between the MATC and the values of EC_(20) and EC_5 reveals that the results from the microcosms are more scientifically-based and more realistic in the sense of environmental protection. Thus, the MATC in the Donghu Lake should be kept below 0.5 ppm or preferably below 0.17 ppm.